Currently, the Network Generation Network (abbreviated as NGN) is a hotspot research topic in the current communication standard field, which employs the IP packet technology as the bearer network technology and converges fixed communication and mobile communication, and thus NGN can provide richer multimedia services, for example, emerging services which has real-time requirements (IP television, video conference, multimedia remote education, video on demand, etc.), and these services require that the communication network can provide support to highly efficient end-to-end quality of service (abbreviated as QoS); and at the same time, the requirements of the user on the quality of service of the network are also higher and higher. Therefore, providing end-to-end quality of service is one of the core problems of NGN.
The International Telecommunications Union-Telecommunications standardization sector (abbreviated as ITU-T) is the telecommunication sector of the International Telecommunications Union and formulates relevant standards on resource and admission control. In the latest Resource and Admission Control Functions (abbreviated as RACF) draft released by ITU-T, the function framework of the RACF is provided, as shown in FIG. 1, RACF consists of two parts, which are respectively Policy Decision Functional Entity (abbreviated as PD-FE) and Transport Resource Control Functional Entity (TRC-FE), wherein TRC-FE interacts with the transport function via Rc and interacts with the Transport Resource Enforcement Functional Entity (abbreviated as TRE-FE) via Rn, and PD-FE interacts with TRC-FE via Rt, interacts with the Customer Premises Network (abbreviated as CPN) via Rh, interacts with the Policy Enforcement Functional Entity (abbreviated as PE-FE) via Rw, interacts with the Service Control Functions (abbreviated as SCF) at the service layer via Rs, interacts with the Network Attachment Control Functions (abbreviated as NACF) via Ru, and PD-FE interacts with the other Next Generation Networks via an Ri interface.
In addition, PD-FE is irrelevant to the transport technology and irrelevant to SCF, PD-FE makes the final decision of resource and admission control based on the network policy rules, service information provided by SCF, transport layer subscription information provided by NACF, and the resource availability decision result provided by TRC-FE.
TRC-FE is irrelevant to the service but relevant to the transport technology. TRC-FE is responsible for collecting and maintaining the transport network information and resource state information. After receiving a resource request from PD-FE, TRC-FE enforces resource based admission control based on QoS, priority demand, resource availability information and transport relevant policy rules.
The transport layer consists of a Policy Enforcement Functional Entity (abbreviated as PE-FE) and a Transport Resource Enforcement Functional Entity (abbreviated as TRE-FE). PE-FE enforces the policy rules issued by PD-FE. PE-FE is a packet to packet gateway and can be located between the Customer Premises Network (abbreviated as CPN) and the access network, between the access network and the core network, or between different operator networks, and it is a key node supporting dynamic QoS control, port address translation control and network address translator (abbreviated as NAT) traversing. TRE-FE enforces the transport resource policy rules issued by TRC-FE, and its scope and function and Rn interface are to be further researched, which does not belong to the research scope of the R2 stage.
3GPP (The 3rd Generation Partnership Project) proposes PCC (Policy Control and Charging) from the view of mobile access to complete the Resource and Admission Control Functions. The key function entity of 3GPP PCC is PCRF (Policy and Charging Rule Function): including policy control decision and control function of charging by traffic. PCRF provides network control functions such as detection, gating, QoS and charging by traffic to relevant service data stream for PCEF (Policy and Charging Enforcement Function).
ITU-T formulates the mobility management and control function (abbreviated as MMCF) and describes the mobility management, control framework and architecture in the NGN transport layer, and this architecture supports the IP mobility of the user equipment in the NGN transport layer; and describes that despite the user uses fixed or mobile access technology, the service continuity is ensured when the terminal attachment points between different access technologies are changed. MMCF supports to interact with RACF (M8 interface), NACF, SCF and transport function.
As shown in FIG. 2, MMCF includes a Mobile Location Management Functional Entity (abbreviated as MLM-FE) which is responsible for location management, location information binding, also includes a Handover Decision and Control Functional Entity (abbreviated as HDC-FE) which is mainly responsible for handover decision, layer 2 handover control and layer 3 handover control; also includes a Network Information Distribution Functional Entity (abbreviated as NID-FE) which is mainly responsible for distributing the handover policy, such as the handover rule parameters defined by the operators; also includes a Network Information Repository Functional Entity (NIR-FE) which is mainly responsible for providing the neighbor access network information, attachment point information and operator policy near the user.
The user accesses the service in the home network and the RACF or PCRF (Policy and Charging Rule Function) of the home network provides QoS support to the user. The location of the user moves and roams to the visit access network, as shown in FIG. 3, the NACF of the visitedvisited network carries out access management authentication on the user and the MMCF carries out handover preparation thereon so as to ensure the continuity of the user service.
When the MMCF is preparing for handover, the MMCF sends to the RACF an available resource query message, which carries the user identifier and a candidate handover access point list; and after having received the query message, the RACF replies with a response message, which carries the user identifier and the resource state of the corresponding candidate handover access point.
In the related art, after the RACF has received the available resource query message from the MMCF, the RACF needs to carry out resource policy decision so as to decide the resources to be allocated to the user, however, the resources allocated to the user by the current resource policy decision method are inaccurate, which may cause to still maintain degraded quality of service for the user when the user roams, thus bringing bad experience to the user.